We wish to compare the process of RNA synthesis (transcription) by three of the oncogenic DNA viruses - polyoma, SV40, and adenovirus 2 - in an effort to discover a step which is required for viral but not cellular transcription. The research is the transcription process. Our approach utilizes a recently devised in vitro system for polyoma transcription which has the important feature of separating most of the viral DNA from cellular chromatin prior to analyzing RNA synthesis. It thus permits a more precise means of localizing and characterizing the active viral template, while still employing the endogenous RNA polymerase and possible necessary factors for viral RNA synthesis. The use of such a system, as opposed to whole cells or nuclei, also has the advantage of permitting the study of the effect of purified macromolecules on the transcription of the viral genome.